Electromagnetic clutch



Aug. 16, 1932. J. COTAL 138713960 ELECTROMAGNETIC CLUTCH Filed April 8.1929 Patented Aug. 16, 1932 7 UNITED STATES PATENT OFFICE.

JEAN COTAL, OF PARIS, FRANCE, ASSIGNOB TO SOCIETE DEXPLOITATION DES BREVETS OOTAL, OEZPARIS, FRANCE ELECTROMAGNETIC CLUTCH Application filedApr1l'8, 1929, Serial N0. 353,551, and in France April 26, 1928.

ture cannot be kept sulficiently small and.

constant to provide for the clutch contact with a small initial excitingaction, such as is necessary to actuate the apparatus in a progressivemanner, for in fact the initial air-gap becomes greater and greater, andin a short time the apparatus must be enerized to such a degree that aviolent contact is the result, so that-the parts are drawn forward in anabrupt manner, and the whole driving gear will be thus subject to severeshocks.

The invention relates to a special clutch device assuring a constant andwell-determined air-gap between the electro-magnet and its armature.

The accompanying drawing shows by way of example a longitudinal sectionof a constructional form of the clutch according to the invention asapplied to a speed changing device.

To the driving shaft 1 is secured an elec tromagnet 2 whose respectivearmature 4 is secured to a toothed wheel 6.

The clutch device comprises a ring 33 which is slidable by easy frictionin the interior of the armature 4, and suitable springs 34 urge the saidring with a suflicient pressure against the internal shoulder 36 of thearmature 4:

The ring 33 comprises an annular projection 37, which makes contact witha corresponding annular projection 38 on the elecb tro-magnet 2, andthis contact takes place at a light pressure produced by a spring 35 Ewhose tension is distinctly less than the sum 1 of the tensions of thesaid springs 34, and thus when in the inoperative position, the saidprojections 37 and;"38 will be in contact 'due to the action 'ofthgespring 35, and the said shoulder 36 ;of the; armature 4 is urged by thesprings against the ring 33, thus ,assuring an air -gapof a few tenthsof a millimeter between the .said armature 4 and its electro-magnet.

Under a weak exciting act-ion, the armature 4 is at once attracted bythe electro-lnagnet 2, thus compressing the springs 34, since theair-gap has but a very small magnetic resistance.

When the exciting action ceases, the arma ture 4 is brought back by thesprings 34 and again makes contact with the ring 33, thus forming withthe electro-magnet 2 an air-gap of a well-determined value. The wearproduced between the contacting surfaces of the armature 4 and of theelectromagnet 2 and which has the tendency to increase the distancebetween the armature 4 and the electromagnet 2 in the-inoperativeposition is compensated by the wear produced between the projections 37and 38 and causing the ring 33 andconsequently the armature 4 to bebrought nearer the electrom'agnet 2. 'The members 6, 4, 33 and 34 arealways rotated as a whole about the axis of shaft 1, so that noappreciable wear is produced between the ring 33 and theshoulder 36.

Havingnow described my invention what I claim as new and desire tosecure by Letters Patent is:

1. An electro-magnetic clutch comprising a driving rotatable shaft, anelectromagnet carried by said driving shaft, an armature for saidelectromagnet rotatably mounted coaxially with relation to said drivingshaft, means for guiding said armature towards and away from saidelectromagnet, a stop member, means adapted to hold said stop member ina fixed position with relation to said electromagnet, and yielding meansadapted to urge said armature against said stop mem- 2. Anelectro-magnetic clutch comprising 3 An e lectro-magnetic eiutchcomprising a driving rotatable shaft, 1m electromagnet carriedby saiddriving shaftjan armature for said electronmgnet rotatably mounted coaxially with relation to said driving shaft. meansfor guiding saidarrflature tpvards and away from said electromagnet; a stogknember,

yielding means bearing at one ehd on said stop member and at the otherend on one side of said armature, whereby said armature is urged againstsaid stop member, and other yielding means of less strength than saidfirst JEAN COTALQ

